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Mechanical injury 2

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Forensic Medicine

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Mechanical injury 2

  1. 1. MECHANICAL INJURIES 1
  2. 2. MECHANICAL INJURIES  Definition: Injuries caused by application of physical violence to the body are known as Mechanical injuries. 2
  3. 3. Classification of Mechanical Injuries Blunt Force Injuries/Trauma: Abrasions. Bruises(Contusions) Lacerations. Sharp Force Injuries/Trauma: Incised wounds. Stab wounds. Chop wounds. Fractures. Fire arm injuries. 3
  4. 4. MANNER OF CAUSATION  Self – Inflicted (suicidal)  Assaults by others (Homicidal)  Accidental 4
  5. 5. ABRASION DEFINITION:  1. It is a superficial injury involving only the superficial layers of skin. (epidermis).  2. The outer layers of skin are scratched or removed leaving a bare area with little or no bleeding.  3. These heal rapidly in few days and leave no scar. 5
  6. 6. MECHANISM OF CAUSATION CAUSED BY a) RUBBING. b) SCRAPING. CAUSATIVE AGENTS. SHARP OBJECTS= FINGER NAILS, PIN, THORN SHARP POINTED OBJECTS. ROUGH SURFACE= GROUND, ROAD, FLOOR. BLUNT OBJECTS= KICK WITH BOOT, ROPES, STICKS, WHIP, TEETH. OF SKIN WITH AN OBJECT 6
  7. 7. CLASSIFICATION OF ABRASIONS  1. Scratches.  2. Grazes. Moving abrasion.  3. Imprint abrasion.  4. Friction abrasion. 7
  8. 8. CLASSIFICATION: a) SCRATCHES:  It is a linear injury caused by a sharp pointed object such as pin or finger nail running across the skin.  CHARACTERISTICS:  The direction of scratch is indicated by sharp edge initially and heaped up epithelium/ epidermis at the end. 8
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  10. 10. CLASSIFICATION OF ABRASION  b) GRAZES / SLIDING/ FRICTIONAL BURNS / GRAVEL RASH :-  It is produced when broad surface of skin slides against a rough surface.  like ground, road also called as brush burns. Example seen in: o Road traffic accidents (RTA). o Dragging of body on a ground. o Glancing kick with a boot 10
  11. 11. MEDICO-LEGAL SIGNIFICANCE:  Direction of force: shown by situation of “tags”.  Identification of scene of incidence: presence of foreign body (dirt or grit) in the graze. Compared with the scene. 11
  12. 12.  c) FRICTION ABRASION: Are caused by rubbing the skin surface with cords or ropes.  Example:  Ligature marks in cases of hanging, strangulation.  Blows with lash.  Friction between skin & edges of garments. 12
  13. 13. CLASSIFICATION OF ABRASION  d) IMPRINT/ STAMPED/ PRESSURE/ CONTACT/PATTERNED/ CRUSHED ABRASION:  It is produced as a result of direct impact or pressure without relative movement.  Example:  Tire mark.  teeth marks.  ligature pattern.  muzzle imprint. 13
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  15. 15. MEDICO-LEGAL SIGNIFICANCE: Identification of offending object. 15
  16. 16. MEDICOLEGAL ASPECTS  It provides valuable information about  1. Site of impact and possibility of internal injury  These indicate that some force has been applied to the body.  2. Identification of Object causing injury  For example as in case of Patterned or imprint abrasions, Ligature in hanging, tire marks in RTA. 16
  17. 17. MEDICOLEGAL ASPECTS  3. Cause of injury  The site of abrasion helps to determine cause of injury, For example;  On Neck in Throttling.  On Nose and mouth in smothering  On thighs and genitalia in sexual assault.  4. Direction of Injury  Sharp margins initial and heaped up epithelium on it, terminate serrated borders initially and heaped up epithelium at the end. 17
  18. 18. DATING AN ABRASION (AGE) OBSERVATION TIME BRIGHT RED FRESH RED SCAB DRIED BLOOD/SERUM 12-24 HOURS. REDDISH BROWN SCAB 2-3 DAYS. HEALING FROM PERIPHERY 4-7 DAYS. COMPLETE HEALING 10-14 DAYS. 18
  19. 19. DIFFERENCE B / W ANTE MORTEM & POST MORTEM ABRASIONS. INDICATOR A.M. P.M. 1. COLOR BROWNISH ON DRYING YELLOW ON DRYING 2. MARGINS. BLURRED (DUE TO VASOCONSTRICTIO N) SHARP 3. VITAL REACTION PRESENT ABSENT 4. SIGNS OF REPAIR PRESENT ABSENT 5. BLEEDING PRESENT ABSENT 19
  20. 20. BRUISE (CONTUSION) DEFINITION:  It is a hemorrhage into the tissues, due to rupture of vessels by the application of blunt force, without breach of covering tissue (skin or capsule). 20
  21. 21. DIAGNOSTIC FEATURES: = Shape may correspond the shape of causative object. = Reddened area when fresh. = Pain. = Swelling. = Size varies from pinhead to an extensive haematoma. 21
  22. 22. CAUSES: 1. SPONTANEOUS (DUE TO DISEASE): Disease of blood, vessels, scurvy, leukaemia. 2. TRAUMATIC: Blows with club, fist, kicks, stone & bricks. Firm griping of weak persons, RTA. 22
  23. 23. CLASSIFICATION OF BRUISE  DEPENDING UPON DEPTH OF THE TISSUE INVOLVED:  Intra dermal bruise.  Subcutaneous bruise.  Deep/delayed bruise /visceral bruise. DEEP BRUISE MAY BECOME EVIDENT AFTER SOME TIME (2-3 DAYS). 23
  24. 24. ECTOPIC BRUISE:  A bruise may not be present necessarily at the site of impact.  The extravasated blood may move along tissue planes under gravity influence and gets collected at a distant place (gravity shifting).  EXAMPLE: - BLOW ON FOREHEAD OR FALL ON VERTEX  BLACK EYE. - FACTURE HEAD OF FEMUR  LATERAL ASPECT OF LOWER THIGH. - BLOW ON OUTER PART OF THIGH  BRUISE AROUND KNEE. 24
  25. 25. SPECTACLE HEMATOMA, BLACK EYE OR PERIORBITAL HEMATOMA OR RACCOON SIGN.  A bruise round the tissues of the eyes & eyelids may result called as Spectacle Hematoma,  It occurs due to  A blow to the orbit  Fractured orbital roof  A blow to the forehead  A fall on the vertex. 25
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  27. 27. BATTLE’S SIGN  A bruise behind the ear called Battle’s Sign may result from fall on the vertex or fracture of the base of the skull rather than a direct blow behind the ear. 27
  28. 28. FACTORS MODIFYING APPEARANCE OF BRUISE  Site of Injury  Vascularity of area  Age  Sex  Color of skin  Nature of disease  Gravity shifting of blood 28
  29. 29. 1. SITE OF INJURY  IMPORTANT SITES 1 Areas covering bones 2 Loose tissue  Bruising more marked in area covering the bones without any intervening fibrous tissue e.g. over tibia.  No bony support for abdominal walls.  Bruising is rare after physical impacts on abdomen.  Absence of bruising is no proof of undamaged underlying tissue/viscera 29
  30. 30.  Bruising appears easily around lax tissue of eyes, face, genitals e.g. Black eye – with a small blow.  Bruise formation on scalp is uncommon except in birth trauma in a new born.  Rare bruising on palm/soles 30
  31. 31. 3) AGE: Children (due to loosening of skin) & old (due to loss of flesh & changes in blood vessels) bruise easily. 4) SEX: Females (obese) bruise easily. 5) VASCULARITY OF PART: Bruising is directly proportional to vascularity of affected part. 6) COMPLEXION: Visibility better and clear in fair skinned people. 31
  32. 32. 7) PRESENCE OF DISEASE.  Coagulation factor deficiency.  Disease of blood vessels.  Diminished platelets (thrombocytopenia).  Persons with nutritional deficiency.  Blood disorders (leukemia)  Arteriosclerosis  Varicose veins.  Obese  Alcoholics 32
  33. 33. MEDICO-LEGAL SIGNIFICANCE  Indicates offending object (blunt).  Gives idea about degree of violence.  Time of injury.  Motive/purpose of injury.  In throttling, pressure of pads of finger  homicide.  Bruise on back of fingers, hand & forearms ( Defensive act).  Multiple small bruise on arms just below shoulders  (Force full grasping during struggle) 33
  34. 34. MEDICO-LEGAL SIGNIFICANCE  Adults: alcoholics, drug dependent.  In children: battered baby syndrome.  Tram track bruise: results from blow with rod, stick or whip & any flexible object. (Torture). Central depressed pale area with margins showing blood & swelling. 34
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  36. 36. MEDICO-LEGAL SIGNIFICANCE  Suction petechie: bruising on the cheeks & breast. (Sexual intercourse),(love bites)  Bruise on the medical aspect of thigh, vulva & around anus indicate forceful sexual intercourse.  Bruising of cervix shows dilatation cervix.  Bruising of buttocks indicate torture 36
  37. 37. MEDICO-LEGAL SIGNIFICANCE  Due to sudden compression of subcutaneous tissues, fat may be displaced and enters into injured vessels lead into fat embolism.  Accidental: common occurrence.  Suicidal: not common.  Homicidal: common  Self inflicted: artificial bruised area produced by rubbing marking nut juice or Calotropis, or root of plumbago over skin. 37
  38. 38. DIFFERENTIATE BETWEEN ARTIFICIAL BRUISE & TRUE BRUISE Findings Artificial Bruise True Bruise Cause Juice of Plant Blunt force Situation On accessible parts Any part Colour Dark brown Changes of colour Margins Well defined Less defined Shape Irregular Shape of weapon Swelling, Redness, & echymosis Not present Present with slight swelling Contents Serum Blood Itching Present Absent Chemical Tests Positive Negative 38
  39. 39. DATING A BRUISE (AGE OF BRUISE) DONE BY: - Macroscopic examination (color changes). - Microscopic examination (blood pigments). Mechanism: Blood, due to disintegration of RBC by haemolysis, releases haemoglobin that breaks down into haemosidrin, haemotoidin & bilirubin by the action of histiocytes & tissue enzymes. 39
  40. 40. DATING A BRUISE (AGE OF BRUISE) CHANGES ARE SEEN FROM PERIPHERY TO CENTER. COLOUR TIME OF INJURY PIGMENT Fresh (Red) Fresh Hemoglobin Red to blue One day Deoxygenated Hemoglobin Bluish black to brown 2-4 Days Hemosiderin Green 5-7 Days Haemotidin Yellow 7-10 Days Billirubbin Completely disappears 14 Days/ 2weeks Normal 40
  41. 41. MICROSCOPIC CHANGES: Hemosidirin within macrophages: not less than 24-48 hours. Hemotoidin within Macrophages: not less than 3 days. Bilirubin extra cellular: not less than 7 days. 41
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